Thermostatic regulator for electric heating elements



y 1950 P. BELGERI 2,508,350

THERMOSTATIC REGULATOR FOR ELECTRIC HEATING ELEMENTS Filed Feb. 17, 1948 Patented May 23, 1950 THERMOSTATIC REGULATOR FOR ELECTRIC HEATING ELEMENTSv Paul Belgeri, Geneva, Switzerland, assignor to Brevets et procds Pyror S. A., Geneva, Switzerland, a corporation 01 Switzerland Application February 17, 1948, Serial No. 8 ,988 In Switzerland February 21, 1947 2 Claims. 1.

This invention relates to a thermostatic regulator for electric heating element, in which the deformations of a bi-metallic element are used to operate a mercury switch controlling the circuit of the said heating element.

This regulator is characterized in that the said switch is carried by an oscillating member, it self mounted on a support which also oscillates, in that the movement of the oscillating member is controlled by the deformations of the bi-metallic element and in that the angular position of the oscillating support is adjusted by hand control, the whole being arranged in such manner that the hand adjustment of the oscillating support permits of varying the length of the time intervals between the periodic closing and opening of the said switch.

The accompanying drawing shows, by way of example, one embodiment of the regulator according to the invention.

Fig. 1 is an elevational diagrammatic view of this embodiment, and

Fig. 2 shows a diagram illustrating two different controls of the temperature of the working apparatus.

The regulator constituting the object of the invention provides for the control of a heating power (such as an electric heating element) by periodical interruptions of the current, the alternating periods of interruption and operation being automatically determined by the deformations of a bi-metallic element provided with an electric resistance constituted by a winding inserted in the controlled circuit, 1. e., the circuit of the electric heating element. l indicates a general hand operated switch, inserted between a terminal D of current supply from a network for example, and the heating element of a working apparatus shown as an electric resistance 2. In the regulator illustrated generally at 3, a mercury switch 4 is provided, the electrodes 5 and 6 of which are respectively connected to the terminal E of the network and to the heating resistance 2. This switch 4 is mounted on bearings 18 provided on a member 1 capable of oscillating about an axis 8 of a support 9 also capable o1 oscillating about an axis It secured to the frame of the regulator 3. The oscillating member I is controlled by the deformations of bi-metallic element I! one end of which is secured to a bracket l2 integral with the support 9, the other end, which is movable, operating by means of an element H' fixed on the said oscillating member I. I3 indicates the heating resistance of the element II and which is connected in parallel with the resistance 2 of the working apparatus. This resistance I3. could also be series connected which would vary' the control of the heating in,- tensity as will be explained hereafter. The oscillating support 9 rests on a cam l4 secured to a shaft I5 on which is fixed a hand operated knob I6 provided with a scale I! turning in front of a fixed guide mark not shown.

The operation of the regulator described is as follows:

Supposing the switch to be closed, the current flows for example from D to E through the heating resistance 2, the resistance l3 of the bi-metallic element I l and the mercury connecting the electrodes 5 and 6.

The movable end of the element I! moves under the effect of heat produced by the passage of the current through the winding 1 3, and causes the member I, resting on the element l to oscillate. The mercury of the switch 4 is set in motion and the current is broken between the two electrodes 5 and 6. In order to realize a more or less rapid action of the bi-metallic element on the switch 4, the initial position or position of rest of the oscillating support 9 may be varied by acting on the cam by means of the knob l6.

It will be noted that the control realized by the regulator herein described (expressed in percentage of heating power) is not directly proportional to the angular displacements of the control knob l 6.

In the diagram shown in Fig. 2, the ordinates correspond to the percentage of the heating power and the abscissae to the angular displacements of the control knob Hi.

The curve A shows, for example, that the heating of the working apparatus increases slowly at the outset and more rapidly towards the end of the angular displacement of the knob IS. The sensibility of control is therefore greater at low intensity, this being of importance when the intensity of the source of heat must be that corresponding to the simmering of a dish, for example. This advantage becomes, on the other hand, a disadvantage if the intensity of the source of heat must be that of an oven. In this case, the shape of the curve must be similar to the B curve (Fig. 2) that is to say that the sensibility control must be greater at the upper part of the curve. The intersecting point C of the curves A and B corresponds to of the heating power. For operation, under one or the other of the intensities, with the automatic regulator described, it is sufiicient either to place the bulb of the switch 4 in the position shown or to reverse its position end 3 to end in the bearings I8, owing to the dissymmetrical shape of the bulb.

By connecting the heating resistance iii of the thermo-couple H in series with the heating resistance 2 of the working apparatus, a control is realized shown by the curve B and by switching this resistance I3 in parallel with the resistance 2.

the control realized is the one shown by the.

curve A.

What I claim is:

1. A thermostatic regulator comprising an cscillatably mounted support, an oscillating member mounted on said support, a mercury switch on said oscillating member, manual means for varying the angular position of said support, a bi-metallic element mounted at one end thereof on said support, energizingmeans for said ele ment, means on the movable end of said element for actuating said oscillating member for making and breaking contact in said mercury switch by oscillation of said member, said manual means upon adjustment to varythe angular position of said support varying the angular position of said mercury switch whereby the period of time in- REFERENCES CITED The following references are of record in the file of this patent:

U STATES PATENTS Number Name Date 1,644,433 Parks Oct. 4, 1927 1,651,629 Phelan Dec. 6, 1927 1,928,907 Noble Oct. 3, 1933 2,012,428 Hollinshead Aug. 27, 1935 2,088,728 Stranszky Aug. 3, 1937 2,224,596 Desfachelles Dec. 10, 1940 

